1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to context-based adaptive binary arithmetic coding (CABAC), and more particularly, to CABAC-based encoding or decoding using improved selection of a context model to obtain a high compression ratio.
2. Description of the Related Art
CABAC is an algorithm used for compressing a motion picture. The CABAC includes selecting a context based on previously input data, performing binary arithmetic coding, and updating statistic information. The context is an environment for collecting the statistic information defined by data symbols that have occurred previously and is used for a precise prediction of occurrence probabilities of occurrences of data symbols.
The compression rate of the CABAC depends on a method of modeling the context. It is advantageous to have a high compression rate, if a probability of occurrence of the least probable symbol (LPS) of the context model becomes low. However, with conventional technology, there is a problem of low efficiency, which results from a slow compression rate of coding, when an input symbol has a value unpredicted in the context model, although the efficiency of coding is high when the input symbol has a value predicted in the context model.